1. Field of the Disclosure
The present disclosure relates to a liquid crystal display device, and more particularly, to a liquid crystal display device which can improve a picture quality.
2. Discussion of the Related Art
In general, the liquid crystal display device displays a picture by controlling a light transmittivity of liquid crystals having dielectric anisotropy with an electric field. The liquid crystal display device controls the light transmittivity of liquid crystals with the electric field for displaying the picture.
Of the liquid crystal display devices, a horizontal field type liquid crystal display device drives the liquid crystals in an in-plane switch mode with a horizontal electric field formed between pixel electrodes and a common electrode arranged in parallel on a lower substrate.
The horizontal field type liquid crystal display device is provided with a thin film transistor substrate and a color filter substrate, which are bonded to face each other, spacers for maintaining a cell gap between the two substrates, and the liquid crystals filled in the cell gap.
The color filter substrate is provided with a color filter for displaying colors, a black matrix for preventing light from leaking, and an alignment film coated thereon for orientation of the liquid crystals.
The thin film transistor substrate is provided with the pixel electrodes and the common electrode arranged in parallel for forming a pixel unit of horizontal electric field, thin film transistors connected to the pixel electrodes respectively, and the alignment film coated thereon for orientation of the liquid crystals.
Referring to FIG. 1, the horizontal filed type liquid crystal display device has a common voltage Vcom of a direct current supplied to the common electrode through a common line arranged parallel to a gate line, and a data voltage Vdata supplied to the pixel electrode for forming a voltage difference with the common voltage.
A related art common electrode supplies a fixed common voltage regardless of positions of liquid crystal cells. In this case, if there is a difference of pixel voltages charged in the liquid crystal cells at different positions caused by a kick back voltage, a line resistance of the common line, or the like, drop of the picture quality is takes place, such as flicker, because the common voltage can not be adjusted for the different positions.